JP4723591B2 - Purification of glycopeptides - Google Patents

Abstract

A novel and improved method for purification of glycopeptides, especially glycopeptide antibiotics. The method comprises contacting a solution of the glycopeptide to an ion exchange chromatography material. The product of this method has a surprisingly high purity.

Description

  The present invention relates to a new and improved purification method for glycopeptides, in particular glycopeptide antibiotics. The method includes contacting the glycopeptide solution with an ion exchange chromatography material. The product obtained in this way has a surprisingly high purity.

Glycopeptide antibiotics can be classified into four groups based on their chemical structure (see, for example, Non-Patent Document 1):
-Group I (or vancomycin system) has aliphatic amino acids at positions 1 and 3;-Group II (or avopalsin system) has aromatic amino acid residues at positions 1 and 3;
-Group III (or the ristocetin system) is similar to Group II but has an ether linkage linking aromatic amino acids at positions 1 and 3;
-Group IV (or teicoplanin system) has fatty acid residues attached to amino sugars in addition to the same amino acid configuration as group III.

  Examples of glycopeptide antibiotics are listed in, for example, Patent Documents 1 and 2, and in these documents, the term dalbaheptide is used for glycopeptide antibiotics. Glycopeptides can be produced by methods disclosed in the art, such as fermentation.

Teicoplanin is actinoplanenes teicomythetics.
was discovered during a scientific research program that seeks to find novel microbial-derived molecules that inhibit bacterial cell wall synthesis (see, for example, Non-Patent Document 2). Teicoplanin was first described in 1978, and 10 years later, it was introduced into clinical practice in Italy (see, for example, Non-Patent Document 3).

  A number of glycopeptide antibiotic purification methods have been disclosed. For example, according to the method disclosed in Patent Document 3, the fermentation broth is adjusted to pH 10 to 11.5 before filtration in order to increase the extraction efficiency of teicoplanin A2. The fermentation broth filtrate is filled in a polyamide resin, and teicoplanin is precipitated from the eluate with an excess amount of acetone, and left for 3 hours. Decant and discard the supernatant and filter the remainder. The obtained cake is washed with acetone to recover teicoplanin A2. This method has the problem that the solvent accumulates due to the use of excess acetone in various steps.

  For example, Patent Document 1 discloses a method for recovering vancomycin-based glycopeptide antibiotics (for example, teicoplanin and vancomycin). In this method, a cation exchange resin having a crosslinking of 2% or less is added to a fermentation broth and added to the resin. Teicoplanin is adsorbed and the mycelium is separated from the resin using a 100 mesh sieve. The resin is then washed with purified water and then eluted to recover teicoplanin.

  For example, Patent Document 4 discloses a method for producing teicoplanin A2, in which the fermentation broth is adjusted to pH 11 and centrifuged, and the supernatant is synthesized with a synthetic adsorption resin such as XAD-16 or HP-20. And adsorbed on activated carbon or silica gel, eluted with 50-80% methanol solution and collected under reduced pressure to obtain teicoplanin as a crude powder. Crude teicoplanin is dissolved in sodium acetate solution and purified by sugar affinity chromatography.

For example, Patent Document 5 discloses a method for purifying teicoplanin A2, which includes (i) a primary prepurification step of purifying a filtrate of a strain fermentation broth using a synthetic adsorbent, and (ii) a hypercrosslinking. A secondary prepurification step of purifying the primary prepurification solution using a cation exchange resin, a catalyst resin or a chelate resin having, and (iii) a final purification step of purifying the secondary prepurification solution using a reverse phase resin; (Iv) a powder molding step.
U.S. Pat. No. 4,845,194A European Patent No. 836619B1 European Patent No. 479086B1 Korean Patent Publication No. 2000-0066479 Specification US Patent Application No. 20040024177A1 Yao, Earl. Sea. (Yao, RC) and Crandall, EL. W. (Crandall, L.W.), "Glycopeptides, Classification, Occurrence, and Discovery in Glycopeptide Antibiotics", Nagarajan, Earl. (Nagarajan, R.), Marcal Decker Inc., New York, NY, Chapter 1, p. 1-27 (1994) Goldstein, B. (Goldstein, B.) et al., “Teicoplanin in Glycoptide Antibiotics”, Nagarajan, Earl. Ed., Marcel Decker, New York, NY, Chapter 8, p. 273-307 (1994) Parent, F. (Parenti, F.) et al. Chemotherapy, Vol. 12, p. 5-14 (2000)

  There remains a need for methods that can be used for mass production of high purity glycopeptide antibiotics. According to the present invention, a high-purity glycopeptide antibiotic can be obtained by a novel ion exchange chromatography method.

  Surprisingly, we have achieved high purity of glycopeptides, particularly glycopeptide antibiotics, by using a method involving ion exchange chromatography of glycopeptide-containing solutions with increased salt concentration and / or conductivity. I found out that Without being bound to a particular theory, it is believed that this method can be used for the purification of all glycopeptides having a common structure, ie, having a dalbapeptide structure.

  This finding provides a method for the purification of glycopeptides, particularly dalbaheptide glycopeptides, using ion exchange chromatography, which increases the salt concentration of glycopeptide solutions to higher levels than previously disclosed. (Thus increasing the conductivity of the solution) and allowing the glycopeptide to bind to the ion exchange resin.

The present invention relates to a method for purifying a glycopeptide antibiotic or a derivative thereof (or a solution containing a glycopeptide antibiotic or a derivative thereof).
(A) performing at least one of adjusting the salt concentration of the glycopeptide solution to at least 0.2 M, or adjusting the conductivity of the glycopeptide solution to at least 20 mS / cm;
(B) contacting the glycopeptide solution with an ion exchange material;
(C) optionally, washing the ion exchange material, and (d) separating the glycopeptide from the ion exchange material using an eluent.

  Glycopeptide antibiotics are oligopeptide (eg, heptapeptide) antibiotics characterized by multiple cyclic peptide backbones optionally substituted with saccharide groups, eg, dalbaheptides, group I glycopeptides (vancomycin series); group II glycopeptides (Avopalsin system); Group III glycopeptide (ristocetin system); Group IV glycopeptide (teicoplanin system); derivatives thereof; individual factors thereof; and preferably an antibiotic selected from the group consisting of combinations thereof . Examples of glycopeptides included in this definition are Raymond Sea. Raymond C. Rao and Louise W. "Glycopeptides Classification, Occurrence, and Discovery" (Drugs and the Pharmaceutical Sciences, Vol. 63, Ramakrishnan narque, ed.) Inc.)]]. Additional examples of glycopeptides include U.S. Pat. Nos. 4,639,433, 4,643,987, 4,497,802, 4,698,327, 5,591, No. 714, No. 5,840,684, and No. 5,843,889; European Patent (Applications) No. 0802198, No. 0801075, No. 0667353; 28812, 97/38702, 98/52589, 98/52592, and J. Org. Amer. Chem. Soc. 1996, Vol. 118, p. 13107-13108; Amer. Chem. Soc. 1997, Vol. 119, p. 12041-12047; Amer. Chem. Soc. 1994, 116, p. 4573-4590. Representative glycopeptides include A477, A35512, A40926, A41030, A42867, A47934, A80407, A82846, A83850, A84575, AB-65, Actaplanin, Actinoidin, Ardacin, Avoparsin, Azureomycin (Azuromycin) Balhimycin, Chloroorientiein, Chloropolisporin, Decaplanin, N-demethylvancomycin, Eremomycin, Galacardine, Helvecaldin, Helvecaldin, Helvecaldin elin), LL-AM374, mannopeptin (MM), MM45289, MM47756, MM47761, MM49721, MM47766, MM55260, MM55266, MM55270, MM56597, MM56598, OA-7653, argentin (R) incine, arbodin (P) Ristomycin, Synmonicin, Teicoplanin, UK-68597, UK-69542, UK-72051, vancomycin and the like, and their derivatives. The most interesting glycopeptide antibiotic to be purified at present is the teicoplanin complex (including factor A2), which is obtained from the fermentation broth.

  It is still more preferred that the glycopeptide is selected from A40926, A84575, Ardacine, Kibdeline, MM55266, parvodisine, vancomycin, teicoplanin complex and its factors, and derivatives thereof.

The term “derivative” means that a substituent directly or indirectly bonded to the cyclic peptide backbone is removed or substituted with another substituent, even though it has a cyclic peptide backbone (eg, a dalbapeptide backbone). And glycopeptides different from those described above. Examples of derivatives include, for example, fully or partially deglycosylated glycopeptides such as aglycone, WO0198328A, 0183521A, 0030607A, 0301608A, 003029270A, European Patent Cited in the art such as Application No. 201251A, US Patent Application No. 20040087494A1, US Pat. No. 5,164,484A, US Pat. No. 5,916,873A, and the above patent documents There are derivatives disclosed in the referenced references.

  Either an anion or a cation exchange material may be used, but the ion exchange material is preferably an anion exchange resin. Among the anion exchange resins, for example, Macroprep (registered trademark) High Q Support [BioRad (BioRad) An anion exchange resin having a high skeleton and a hydrophilic structure is still more preferable.

  The conductivity of the glycopeptide solution is preferably 15 mS / cm or more, more preferably 20 mS / cm or more, 25 mS / cm or more, or 30 mS / cm or more. The conductivity can be 40 mS / cm or higher.

  The salt concentration during ion exchange is higher than about 0.25M, for example, preferably higher than 0.30M or even higher than 0.35M or 0.45M, and the salt concentration during ion exchange is about 2 Preferably it is below 0.0M, for example below 1.5M, below 1.0M or even below 0.7M. The salt concentration is preferably within the range of 0.4 to 0.7M. NaCl adjustment can be performed by measuring the added salt.

Examples of salts that can be used to adjust the salt concentration and / or conductivity of the solution in connection with the present invention include, for example, the following anions: Cl ⁻ , HSO ³⁻ , BrO ³⁻ , Br ⁻ , NO ³⁻ , An alkali metal salt selected from the group consisting of sodium salt, potassium salt or lithium salt of ClO ³⁻ , HSO ⁴⁻ , HCO ³⁻ , IO ³⁻ , HPO ⁴⁻ , formic acid, acetic acid and propionic acid; is there. At present, NaCl is preferred. Mixtures of various salts may be used.

Examples of eluents that can be used (particularly in connection with anion exchange resins) include:
For example,
(A) a weak organic acid, preferably acetic acid or citric acid, or (B) an acid such as an acid selected from the group consisting of a weak organic acid and a corresponding base, preferably a buffer solution having a pH of 4.5 or lower; ,
There are salt solutions including salts such as the above salts, and mixtures thereof.

  The eluent is acetic acid and / or the acid concentration is preferably higher than 0.1M (eg higher than 0.3M, 0.5M, 0.8M) and the acid concentration should be higher than 1.0M. preferable. However, the acid concentration must be less than 6.0M, and more preferably less than 4.0M. Mixtures of various acids may be used. When using an aqueous salt solution as the eluent, the salt concentration is preferably higher than 1.5M. The eluent is acetic acid and / or the acid concentration is preferably 0.1-6.0M, more preferably 1.0-4.0M. Mixtures of various acids may be used.

Embodiments of the invention relate to a method as described above, which further comprises the following steps:
(A) obtaining a crude fermentation broth containing glycopeptide antibiotic-producing microorganisms, (b) adjusting the pH of the crude fermentation broth to pH 8-12, and (c) a glycopeptide, for example by centrifugation or filtration Separating the fermentation broth from the antibiotic-producing microorganism (mycelium mass) to obtain a glycopeptide antibiotic-containing solution.

The pH is adjusted to 9-11 and the separation is preferably carried out at a temperature of 0-25 ° C, and the separation is more preferably carried out at a temperature of 5-15 ° C.
The method of the present invention comprises one or more purification steps to obtain a purer glycopeptide, for example
(A) reverse phase chromatography, eg HPLC,
(B) adsorption chromatography,
(C) filtration,
(D) reverse osmosis,
(E) Decolorization by treatment with activated carbon or adsorption resin,
(F) cation exchange chromatography,
(H) precipitation,
(I) centrifugation,
It may comprise a purification step selected from the group consisting of (j) affinity chromatography, and (k) liquid-liquid extraction, or for example a purification step selected from (a) to (i) above.

The solid glycopeptide can be isolated from the purified solution by methods well known to those skilled in the art, such as lyophilization.
In the context of the description of the invention (especially in the context of the claims), the terms “a” (“a”, “an”) and “its” (“the”) and similar designations are Unless otherwise specified in the specification or unless clearly contradicted by context, the singular and plural are considered to be included. The terms “comprising”, “having”, “having”, “including” and “containing” are open-ended unless otherwise indicated. It shall be interpreted as a term (ie, “including” means “not limited to”). The recitation of numerical ranges herein is merely intended as a convenient way to individually refer to each individual value encompassed within the range, unless otherwise indicated herein. One value is incorporated herein as if it were individually listed herein. All values specified herein are to be interpreted as “approximately” values, eg, “2.0M” should be interpreted as “about 2.0M”.

  All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. Any and all examples or language used in the specification (e.g., "such as") is intended to merely clarify the invention unless otherwise indicated. However, it is not intended to limit the scope of the present invention. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

  Experiment

Preparation of Teicoplanin Aqueous Solution Example 1a
In a manner known per se, for example as disclosed in US Pat. No. 4,239,751, A.I. A teicomycetics culture is fermented to obtain a teicoplanin-containing fermentation broth.

  5 L teicoplanin-containing whole culture fermentation broth from a laboratory fermenter was adjusted to pH 9.5 (with 1 M NaOH) and stirred. This solution was filtered through a 100 μm depth filter (Polygard ™, Millipore) at room temperature, followed by ultrafiltration (500,000 Da, Biomax ™, Millipore) at 12-14 ° C. )did. Residual teicoplanin was recovered by diafiltration of the biomass in batch mode using 4 × 0.5 L of water. About 80% of the teicoplanin present in the fermentation broth was recovered in the final clear solution.

Example 1b
1M NaOH was added to 500 ml of teicoplanin fermentation broth obtained in the same manner as in Example 1a to adjust the pH to 9.5, and centrifuged at 10 ° C. with a laboratory centrifuge to obtain a cell-free solution. About 85% of the teicoplanin present in the fermentation broth was recovered in the final clear solution.

Ion Exchange Chromatographic Purification Example 2a: Anion Exchange Chromatographic Purification of Teicoplanin Factor A2 (TA2) To a clear teicoplanin solution from Example 1a containing 0.5 g of product, adjusted to pH 8 by adding 1M HCl. . NaCl was added to a final concentration of 0.5 M, and a conductivity of about 50 mS / cm was obtained. Methacrylate copolymer anion exchange resin Macro-prep (registered trademark) High Q Support (Bio-Rad) was packed into a chromatography column (inner diameter (id) 1.6 cm, bed height 12 cm, volume 24 ml), and this column was prepared. Teicoplanin solution was added at a flow rate of 3.4 ml / min. The column was washed with 48 ml of 0.5 M NaCl solution and then the product was eluted with 192 ml of 3 M acetic acid. Although 0.42 g of teicoplanin was recovered in the elution pool, the HPLC purity of the pool was improved from about 70 area% to 90 area% TA2 when a considerable amount of coloring component was removed in conjunction with this operation.

  Optionally, incorporating a wash step that includes high NaCl concentrations (ie, concentrations up to 2M) into this chromatographic process further increases the purity and color of the final product pool, but the loss of teicoplanin is There was very little.

Example 2b: Anion exchange chromatographic purification of TA2 1M HCl was added to a clear teicoplanin solution from Example 1a containing 0.5 g of product to adjust to pH8. NaCl was added to a final concentration of 0.5 M, and a conductivity of about 50 mS / cm was obtained. Pack an agarose-based anion exchange resin Q-Separose ™ Fast Flow (Amersham Biosciences) into a chromatography column (inner diameter (id) 1.6 cm, bed height 12 cm, volume 24 ml) The prepared teicoplanin solution was added to this column at a flow rate of 3.4 ml / min. The column was washed with 48 ml of 0.5 M NaCl solution and then the product was eluted with 192 ml of 3 M acetic acid. 0.35 g of teicoplanin was recovered in the elution pool, but the HPLC purity of the pool was improved to about 85 area% TA2.

Example 2c: TA2 by adding NaHCO ₃ to a transparent teicoplanin solution from Example 1a containing product of anion exchange chromatography 0.5g for purifying a concentration 0.7M, the solution was added 1M HCl The pH of the is adjusted to 8. This solution is then added to the column as described in Example 2b. The column is washed with 48 ml of 0.7M NaHCO ₃ solution and eluted with 192 ml of 3M acetic acid. Purified teicoplanin is recovered in the elution pool.

Example 2d Anion Exchange Chromatography to Purify Vancomycin A crude fermentation broth containing vancomycin can be produced and clarified by centrifugation according to the procedure of US Pat. No. 5,223,413. NaCl is added to a clear vancomycin solution containing 0.5 g of product to a concentration of 0.5 M, and the pH of the solution is adjusted to pH 10 (adding 1 M NaOH). The vancomycin solution is then added to the column as described in Example 2a. The column is washed with 48 ml of 0.5 M NaCl solution, and then the desired product is eluted with 192 ml of 0.5 M acetic acid. Purified vancomycin is recovered in the elution pool.

Example 2e: Cation Exchange Chromatography 1M HCl is added to the clear teicoplanin solution from Example 1a containing 0.5 g of product to adjust the pH to 2.8. NaCl is added to a final concentration of 0.3M. The solution is added to a column (id 1.6 cm, bed height 12 cm, volume 24 ml) packed with methacrylate copolymer cation exchange resin, ie, Macro-prep® High S Support (Biorad). The column is washed with 48 ml of 0.3 M NaCl solution and the target is then eluted with 192 ml of 0.2 M sodium acetate at pH 6.0. Purified teicoplanin is recovered in the elution pool.

  Teicoplanin was produced by fermentation and clarified as described in Example 1a. An equal amount of clear broth containing 1.0 g teicoplanin was mixed with various amounts of NaCl (see Table 1 below) to make 0-1 M NaCl in solution. After lysis, the sample was applied to the column at a flow rate of 3.4 ml / min as described in Example 2a. The column was washed with an equimolar concentration of 48 ml of NaCl solution, and the target product was eluted with 192 ml of 3M acetic acid. The binding capacity and HPLC purity of teicoplanin were measured by standard HPLC methods. The pool was selected so that the area percentage of TA2 was about 90%.

  The results are summarized in Table 1 below:

Additional purification The clear (eg after filtration or centrifugation) fermentation broth can be purified prior to being subjected to an ion exchange step and / or the solution from the ion exchange step is known per se, eg Additional purification can be performed using one or more purification methods as described below.

Example 4a: Prepurification of teicoplanin prior to anion exchange-loading on hydrophobic skeleton Adjust the pH to 8 by adding 1 M HCl to the clear teicoplanin solution from Example 1a containing 0.5 g of product, A flow rate of 0.7 ml in a column (inner diameter (id) 1.6 cm, height 10 cm, volume 20 ml) packed with a giant network aliphatic cross-linked polymer [XAD7HP, Rohm & Haas] Add in minutes. After binding, the column is washed with 80 ml of water and then eluted with 100 ml of a 50/50 mixture of ethanol and water to recover teicoplanin. The eluate obtained is evaporated at 40 ° C. and 80 mbar using a rotary evaporator. The resulting ethanol-free solution is treated as described in Example 2a.

Example 4b: Additional purification of TA2 in an ion exchange pool by loading onto a hydrophobic interaction resin A column with a diameter of 1.6 cm and a bed height of 10 cm (volume 20 ml) was loaded with a hydrophobic interaction resin, namely Octyl Sepharose ™ ) Fill with Fast Flow (Amersham Biosciences). Ammonium sulfate is added to the elution pool from Example 2a to a concentration of 0.1M, and the column is loaded at pH 2.5 with a flow rate of 2.5 ml / min. The column is washed with 40 ml 0.1 M ammonium sulfate solution and eluted with 120 ml water. In this operation, a light-colored purified teicoplanin solution is recovered.

Example 4c: Additional purification of TA2 in the ion exchange pool by loading on a cation exchange resin From one of Examples 2a-2c containing 0.35-0.45 g teicoplanin in acetic acid solution (pH 2.5) The product is added to a cation exchange resin [Macro-prep® High S Support (Biorad), id 1.6 cm, height 10 cm, volume 20 ml] at a flow rate of 2.5 ml / min. After washing the column with 40 ml of 0.1 M acetic acid solution, the target is eluted with 120 ml of 0.2 M sodium acetate, pH 6.0. Purified teicoplanin is recovered in the elution pool.

Example 4d: Decolorization of TA2 in the ion exchange pool by carbon filtration The elution pool recovered in Example 2a was added to 75 ml of ethanol to form a 50/50 vol% mixture, and then an immobilized activated carbon filter (millistak + (registered) Trademark), 13 cm ² filtration area, Millipore). The filter was rinsed with 25 ml of 50/50 vol% water / ethanol mixture. Teicoplanin was recovered in a nearly colorless product solution.

Example 4e: Decolorization of TA2 in the ion exchange pool by size exclusion chromatography 10 ml of the elution pool from Example 2a was applied to a 30 ml size exclusion column (Superdex ™ 30 prepgrade, Amersham Biosciences) Load at a flow rate of 1 ml / min. Colored components larger than teicoplanin in the sample are eluted and removed prior to teicoplanin.

Example 4f: Precipitation of TA2 in the ion exchange pool by addition of organic solvent Teicoplanin in the elution pool from Example 2a is precipitated from the solution by adding 1370 ml of acetone to a final concentration of 95%. The sediment is harvested by filtration and the resulting filter cake is washed twice with 10 ml of acetone. The filter cake is then dried at 40 ° C. in a vacuum oven. The purified teicoplanin is recovered with a dry filter cake.

  This specification describes preferred embodiments of the invention, including the best mode known to the inventors for carrying out the invention. From reading the above description, variations on these preferred embodiments will become apparent to those skilled in the art. Skilled technicians can scale up the methods disclosed herein. The inventors expect that skilled technicians will use such variations as needed, and that the invention is implemented in a manner different from that specifically described herein. It is also intended. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. All the above patent documents and scientific papers are incorporated herein by reference in their entirety.

Claims (21)

A method for purifying glycopeptide antibiotics, comprising:
(A) performing at least one of adjusting the salt concentration of the glycopeptide solution to at least 0.2 M, or adjusting the conductivity of the glycopeptide solution to at least 20 mS / cm;
(B) contacting the glycopeptide solution with an ion exchange material; and
(C) A method comprising the step of separating a glycopeptide from an ion exchange material using an eluent. The method for purifying a glycopeptide antibiotic according to claim 1, further comprising a step of washing the ion exchange material after step (b). The method of Claim 1 which adjusts the electrical conductivity of a glycopeptide solution to 20 mS / cm or more. Glycopeptide antibiotics are dalbaheptides, group I glycopeptides (vancomycins); group II glycopeptides (avopulsin); group III glycopeptides (ristocetin); group IV glycopeptides (teicoplanin); their individual factors; The method of any one of claims 1 to 3, selected from the group consisting of: derivatives thereof; and combinations thereof. The method according to any one of claims 1 to 4, wherein the glycopeptide antibiotic is selected from the group consisting of teicoplanin and vancomycin. The method according to any one of claims 1 to 5, wherein the ion exchange material is an anion exchange resin, preferably an anion exchange resin in which the skeleton has polymer hydrophilicity. The method according to claim 1, wherein the conductivity of the glycopeptide solution is 30 mS / cm or more. The method according to claim 1, wherein the salt concentration during ion exchange is higher than 0.3M. The method according to claim 1, wherein the salt concentration during ion exchange is lower than 1.5M. The method according to any one of claims 1 to 9, wherein a salt is added to adjust at least one of a salt concentration and a conductivity of the solution. The salt comprises the following anion: Cl ⁻ , HSO ^3- , BrO ^3- , Br ⁻ , NO ₃ ⁻ , ClO ₃ ⁻ , HSO ₄ ⁻ , HCO ₃ ⁻ , IO ₃ ⁻ , HPO ₄ ^2- 11. The method of claim 10, wherein the salt is selected from a salt such as an alkali metal salt selected from the group consisting of sodium, potassium or lithium salts of one of formic acid, acetic acid, and propionic acid. The method of claim 10, wherein the salt is NaCl. 13. A method according to any one of claims 1 to 12, wherein the eluent is an acid or salt solution. Eluent
(A) a weak organic acid, and
(B) Buffer consisting of weak organic acid and corresponding base
The method according to any one of claims 1 to 13, which is an acid selected from the group consisting of: 15. A method according to claim 14, wherein the weak organic acid is acetic acid or citric acid. The method according to claim 14, wherein the buffer solution has a pH of 4.5 or less. 15. The method of claim 14, wherein the acid concentration is in the range of 0.1M to 5.0M. The method of claim 1, further comprising adding an organic solvent to precipitate TA2. The method of claim 18, wherein the organic solvent is acetone. A method of using a solution comprising a glycopeptide antibiotic, wherein the solution comprising the glycopeptide antibiotic is used for ion exchange purification of the glycopeptide antibiotic, wherein the salt concentration of the solution is at least 0.2M. Or at least one of the conductivity of the solution is at least 20 mS / cm. 21. The method of use according to claim 20, wherein the glycopeptide antibiotic is selected from the group consisting of teicoplanin and vancomycin.